Major automobile manufacturers are continuing their development of cars powered by fuel cells using hydrogen (reference 1). Like cars powered by electric batteries the cars themselves will emit no greenhouse gas (GHG). Bulk quantities of hydrogen are mainly derived from natural gas (increasingly frackgas) but the process results in the production of carbon dioxide, a GHG, so fuel cell cars will not reduce overall GHG emissions. However hydrogen can also be produced from the electrolysis of water using electricity. If this electricity is generated from a power grid of non-fossil fuelled generation then zero overall GHG emissions can be achieved – this applies to battery cars as well as fuel cell cars.

Since fuel cell cars and battery cars can significantly reduce GHG emissions in at least part of the transportation sector the market for such vehicles could expand and one of the key questions will be how will these cars affect the demand for electricity and the stability of the grid. Battery cars and fuel cell cars will affect the power grid in different ways. Battery charging is uncontrolled and people will charge their car batteries when convenient, day and night. Fast battery charging at home from a dedicated house circuit can overload the street transformers. Smart controls at the distribution level may alleviate this but ultimately the distribution system might need upgrading to handle the extra demand. All ratepayers will pay for this including those without battery cars. Increasing the day time peak loads on the grid by uncontrolled battery charging will require an increase in generating capacity, likely from frackgas-fired GHG emitting units. Ideally battery charging should be done overnight when surplus generation is available at the lowest carbon dioxide emission intensity and at lowest cost.

The production of hydrogen for fuel cell vehicles (cars, trucks, buses, forklifts etc.) can be controlled so surplus night time and weekend generation can be used when carbon dioxide emission intensity is lower and prices are lower. Hydrogen production facilities would be ideal demand response loads to help stabilize the grid. Ontario is in the fortunate position of having a grid that has about 80 percent of its generation coming from GHG free nuclear and hydro. This could be increased to practically 100 percent GHG free if more nuclear were installed (reference 2). Dependable night time nuclear generation could also produce hydrogen that can be stored for use in turbine generators to provide for the peak load the following day instead of using gas-fired generation. Wind would not be reliable enough to do this. The production of hydrogen overnight from the additional nuclear plants, that would replace the gas-fired plants, would enable nuclear to operate efficiently at full capacity day and night and compressed air could also be produced and used with the hydrogen in these turbine generators if economics justify. Stationary fuel cells could also be used to generate electricity as well as providing a source of heat. The Enhanced CANDU 6, proposed for Darlington B, is extremely flexible (reference 3) and this flexibility combined with hydroelectric generation and the demand response capacity of the hydrogen producing facilities would give Ontario the world’s cleanest and most flexible power grid.

In the future nuclear reactors operating at much higher temperatures than present day units will enable hydrogen to be produced more efficiently. As far as the Ontario grid is concerned it looks like fuel cell cars would be of more benefit than battery cars. The Ontario government is actively promoting electric battery cars (reference 4) at ratepayers expense but maybe it should be promoting fuel cell cars instead, for the good of the electricity grid and maybe the ratepayer. Larger vehicles like big trucks may find hydrogen more practical than batteries. Of course there are many other things to consider when comparing battery and fuel cell cars besides the impact on Ontario’s electricity supply system. This is an area that needs more detailed study and should be included in Ontario’s next Long-Term Energy Plan. The aim should be to reduce life cycle GHG emissions. Maybe “The Hydrogen Economy” is not dead.References

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This entry was posted on Tuesday, November 25th, 2014 at 7:40 am and is filed under Grid. You can follow any responses to this entry through the RSS 2.0 feed.
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